it's both easy and hard I guess.
The concept it's easy to understand and use, but can take long steps to setup as you first need to test and be sure each or your nands are working properly BEFORE installing wads to each of them.
A) first, create two emuNAND :
1. by editing the EmuNAND path in usbgx settings, dump your own nand, one of which will be your "main".
2. if you need neek for games from another region, you'd better generate a new empty clean NAND for that specific region with modmii, and put it on your device too, in another folder.
You could dump your own NAND and then set neek's hidden menu "region free" but it might not work with all games. up to you to test!
for example :
nands/nand1/
nands/nand2/
or
nands/mine/
nands/eur/
or
nands/mine/
nands/neek_eur/
nands/neek_jpn/
nands/neek_usa/
or whatever you like, as long as you understand what folders and subfolders are.
B)
Install ALL your games (working and non working) to your "main" emuNAND.
C)
install non working games (YES, again, install them twice!) to specific emuNAND (by editing the emuNAND path in usbgx before installing the WAD, or using ShowMiiWad tool on PC)
D)
display your "main" emuNAND in USBGX to display all your games.
select the game which is not working with your main setup, go to its settings, change the "emuNAND path" to use the proper path (for example, if it's a jpn game, you'll want it to use your neek_jpn folder).
select whether you want that game to use Full emuNAND mode, or neek mode.
you understand the idea?
You see ALL your library without the need to change the displayed path every time, and each game can use individual folders, and setup (full emuNAND, or neek mode).
that's just a lazy mode, you could just change the displayed path whenever you need it instead of installing all games multiple times and changing their settings one by one.
Of course, you FIRST need to setup neek properly, with proper video mode settings, region free or not, etc. and be sure it WORKS and BOOTS, BEFORE installing wads to it !
doing things randomly, or in wrong order, or in haste because you want things quickly and think you can skip steps, or following blindly a guide without understanding WHY you do something, is sure to make your setup not working. you need to think by yourself a little and understand what you are doing. if you don't understand and just "push buttons" because a guide tells you to "press A, A , B and A again" without reading the on screen info, you are doing things wrong and shouldn't mod any consoles.
To answer previous users from December :
if you install a WAD on real NAND, and move it to SD menu, you'll need your SysMenu to use a patched IOS. cIOS70 or cIOS80 based on the one you are using. run syscheck to verify if your IOS is official or patched. do NOT install random files for the wrong console ! do not mix Wii, vWii and wii-mini guides!
SD menu installed games can't be launched from a loader (yet). you might see them listed, but it won't launch! it requires a "game decompressing and installation to SysNAND" before being launched. if you don't have enough free space on your internal memory, it'll not work.